Automobiles are typically provided with passenger compartment air systems which can provide fresh and/or recirculated air to the passenger compartment for passenger comfort. Typically, at least a portion of this air is introduced into the passenger compartment through vents which include control surfaces such as a damper, control vanes and louvers that can be adjusted by the passengers to select a flow rate and to direct the air to a desired direction.
In the past, a variety of mechanisms have been provided to passengers to operate these control surfaces and one of the more popular mechanisms is a control wheel which can be rotated by the passenger with their thumb or finger. A control, typically a shaft, cable or other linkage, extends between the control wheel and the control surface and is moved when the control wheel is operated to appropriately move the control surface. Ideally, such a control wheel will be inexpensive to manufacture, easy to assemble, easy to operate and will remain in a selected position until intentionally moved to another position by a passenger.
A prior control wheel constructed by the assignee of the present invention employed a resilient bushing mounted in the wheel and riding on the shaft about which the control wheel rotates to provide the frictional force to maintain the control wheel in the position it was put in by the passenger and to isolate, to at least some extent, the control wheel from vibrations of the automobile. However, this control wheel suffered from disadvantages in that the resilient bushing and the receptacle in the wheel in which it is mounted and the shaft which it engages are subject to manufacturing and/or thermal tolerances which can result in different control wheels experiencing different frictional forces, which is undesirable. Manufacturing tolerances can result in the bushing being compressed, or loose, when installed in the receptacle in the wheel with the result that the bushing will be too tight or too loose on the shaft. Similarly, the tolerances can change, due to the effects of temperature changes in the passenger compartment, which expand or contract the bushing and other components.
It is desired to have a control wheel which is reasonably inexpensive to manufacture and whose operation is acceptable despite minor changes in tolerances of the components of the control wheel.